Simplified VC/NVA command structure Image is a self-made powerpoint screenshot- a bunch of Powerpoint boxes for the diagram, Powerpoint clipart icons for ships etc, and inset photo and map from a government agency in the public domain- from US Govt Document -The Army Engineer in Vietnam, The U.S. Army Engineer School, Fort Belvoir, VA. US ARMY CORPS OF ENGINEERS- Office of History and US Army: [1]. Military clipart icons from US Army website- Fort Sill. All are public domain https://sill-www.army.mil/Graphics/clipart_library.htm

Since Powerpoint is used the following blurb satisfies Microsoft requirements re clipart use: "Contains clipart from Microsoft Powerpoint- not for commercial use or resale, per Microsoft guidelines at http://office.microsoft.com/en-us/powerpoint/HP030900871033.aspx, Copyright, Microsoft Corporation. Include this notice with any reuse."